I'd like to create beams of electricity between two points very similar to this video: http://www.youtube.com/watch?v=eMJ8-56L3Lc. The effect is so dynamic, with varying lengths and pseudo-random movement in-between the points, that I'm having trouble imagining how I'd accomplish such a thing. Is there any helpful information that might point me in the right direction?

I should note that I'm using the XNA 4.0 Reach profile, but custom shaders are okay because I'm not targeting the Windows Phone.